1. Field of the Invention
The present invention relates to a winding method and a winding apparatus for adding layers to a transformer. More particularly, the present invention relates to a method and an apparatus for alternatively winding a linear wire and a film web in the form of multiple layers for a bobbin type transformer such as a flyback transformer.
2. Description of the Related Art
Japanese Patent Application Laid-Open Nos. Hei 5-3128 and Hei 5-101961 disclose the following conventional techniques in the field to which the present invention pertains.
Japanese Patent Application Laid-Open No. Hei 5-3128 relates to the manufacture of a compact winding device fit for mass-production by a method wherein a core holding mechanism is composed of intermittently rotated frame body and multiple core fixing spindles rotatable and projecting from the periphery of the frame body respectively provided with a specific wire winding mechanism and a sheet winding mechanism.
The barrel of a core is alternately wound up with a conductive wire and an insulating sheet using a core holding mechanism, a wire winding mechanism and a sheet winding mechanism so as to form a laminated layer coil. In such a device, the core holding mechanism is composed of an intermittently rotated frame body and multiple core fixing spindles rotatable and projecting from the periphery of the frame body. A wire winding mechanism for winding the wire around the terminal of the core in every layer winding step is arranged in the position opposing to one of the spindles while a sheet winding mechanism is arranged in the position opposing to one of the other spindles.
Japanese Patent Application Laid-Open No. Hei 5-101961 provides appartus to rapidly supply an insulation film tape to a coil bobbin engaged with a spindle.
An insulation film tape from a supply source is necessarily processed, its end is made to approach and remain near a tape winding part. Then, when a coil bobbin is moved to the winding part, it is supplied to a predetermined position of the bobbin, and fusion-bonded. It is cut in a predetermined length to obtain a cut tape. Thereafter, the bobbin is rotated, a rear nip for holding tape is moved together with the tape and wound.
As disclosed in Japanese Patent Application Laid-Open No. Hei 5-3128, in particular, in the technique in forming multiple laminated layers by alternatively winding a wire and a sheet, a change in thickness of the winding layer in the winding step to the bobbin is accommodated with a mechanism for pressing the film at a certain pressure with the fusion-bonding mechanism. Also, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-101961, in the winding method, the film is cut after the film is pressed to the bobbin by the fusion-bonding mechanism. Thereafter, the bobbin is rotated.
However, in the conventional fusion mechanism, it is insufficient to press the film to a certain extent and it is difficult to accurately fusion-bond the film to a preselected position. For this reason, there is a problem that the shape of the final transformers is considerably upstable.
Also, if the film is cut after the film has been pressed to the bobbin by the fusion-mechanism, it is impossible to control the length of the film to be wound, due to the varying thickness of the winding layer. As a result, there is a problem that the shape of the final transformers becomes irregular, thus decreasing the energy transforming efficiency.